Problem: Luis ate 4 slices of pizza. Nadia ate 5 slices. If there were 1 slice remaining, what fraction of the pizza was eaten?
Answer: $\text{fraction of pizza eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ Since they ate 9 slices of pizza with 1 slice remaining, they must have begun with 10 slices. They ate ${9}$ out of $10$ slices. They ate $\dfrac{9}{10}$ of the pizza.